Hydraulic reaction power amplification



April 2l, 1959 w. H. PAYNE HYDRAULIC REACTION PowER AMrfLIFIcATIoN 4Sheets-Sheet 1 Fi1 ed Aug. 5, 1955 April 2l, 1959 w. H. PAYNE HYDRAULICREACTION PowEP. AMPLIFICATION 4 Sheets-Sheet 2 Filed Aug. 5. 1955 ilmwmi.l

April 21, 1959 w. H. PAYNE HYDRAULIC REACTION PowEP. AMPLIFICATION 4Sheets-Sheet 3 Filed Aug. 5, 1955 INVENTOR. Mgg/Mama? /gn a@ April 2l,1959 w. H. PAYNE HYDRAULIC REACTION POWER AMPLIFICATION 4 Sheets-Sheet 4Filed Aug. 5, 1955 INVENTOR.

United States Patent G HYDRAULIC REACTION POWER AMPLIFICATION WilliamHarvey Payne, Pine Hall, N.C.

Application August 5, 1955, Serial No. 526,713

Claims. (Cl. 137-83) There have long been many instances in which heavyapparatus or a heavy force must be controlled by a delicate controlforce, so that some form of amplification of force is necessary.According to the present invention, a simple hydraulic mechanism isdevised by which it is possible to amplify or increase a relativelysmall primary input force, to any degree, so that it will proportionallymove a heavy output shaft or secondary force by hydraulic reactionpower.

'I'he specific arrangements of the invention disclosed herein, lendthemselves best to the use of high pressure hydraulic reactionamplification, and yet it avoids the problem of oil foaming which isencountered even in some low-pressure jet-moving apparatus now in use.

The invention disclosed herein has few parts, is rugged mechanically,and should have low or negligible upkeep costs.

It may have a valuable application wherever it is desirable to moveheavy apparatus from a Weak primary force.

As an example of almost necessary usage, my Patent 2,657,327,"AdjustingrSystem for Furnace Controls, has in its structure a pistonvalve which must be moved accurately in reversing angular motions, witha block position at its movement mid-point. This high pressure valvepiston is not easy to move, yet the more satisfactory operation underthat ne patent depends on my ability to amplify the small signal of afree-moving currentvoltage torque motor, so that the heavy valve pistonwill follow every angular movement of the torque motor.

Another example of the use of this invention is that of a power assistto ease hand power in vehicular steering. This power assist design lendsitself to steering with a feel of the road. l

The illustrations herein show the primary force shaft in line androtative with the secondary or output shaft. This permits simple reservemechanical coupling, which is useful in the case of hydraulic failure.It is not intended, however, that a relative change of position of thesetwo shafts will avoid this invention.

Although the illustrations with this disclosure all show rotative orangularly moving primary and secondary output shaft arrangements, thisinvention may be applied to non-circular movements.

Among the objects of this invention is an arrangement which amplies thesmall power or force applied to turn an angular moving input shafthydraulically, so that its associated heavy output shaft, having eithera leading or lagging load, will always follow every change in theposition of the input shaft.

Another object of this invention is that arrangement wherein thehydraulic assist power is applied to the output shaft in a varyingdegree of power value, as is needed to always keep the output shaftrotatively aligned with the input shaft.

Another object of this invention is to associate the input shaft withthe output shaft mechanically, so that in 2,882,917. Patented Apr. 21,1959 ICC the case of hydraulic power failure, one shaft can still beused to move the other.

Another important object of this invention is that of a power assistsuitable to help move a vehicle steering apparatus.

Another object of some forms of this invention, when used as a steeringwheel assist, is that of giving a feel" to the steering effort, as willbe described later.

The foregoing and other important objects, advantages and inherentfunctions of the invention will become apparent as the same is morefully understood from the following description and the accompanyingdrawings, which disclose preferred embodiments of the present invention.

Designation of figures Fig. l is a side elevation partially in section,of a representative industrial hydraulic load moving system, containingone form of my invention.

Figs. 2, 3 and 4 show side, plan and end views, in larger detail of theform of my invention shown in small scale in Fig. l. Fragmentary views3a and 3b show the parts positioned for counterclockwise control.

Figs. 5, 6 and 7 illustrate details of another arrangement of myinvention. Fig. 5 shows an end or face view. Fig. 6 shows an axialsectional view approximately along line 6 6 of Fig. 5. Fig. 7 shows alongitudinal cross section through the reaction unit, approximatelythrough section 7--7 of Fig. 6.

Figs. 8, 9 and 10 illustrate a third arrangement of this invention inenlarged detail. Fig. 8 shows a fragmentary end elevation, with asection through the input shaft. Fig. 9 is a view from the samedirection but with the enclosure removed, and with the input shaft andthe reaction blades positioned for clockwise power assist. Fig. l0 showsa cross section approximately in an axial plane.

All of the above figures show arrangements of hydraulic reaction poweramplifying, to illustrate their operation.

Although the law requires a full and exact description of at least oneform of the invention, such as that which follows, it is, of course, onepurpose of a patent to cover each new inventive concept therein nomatter how it may later be disguised by variations in form or additionsof further improvements; and the appended claims are intended toaccomplish this purpose by particularly pointing out the parts,improvements, or combination in which the inventive concepts are found.

Description and operation One example of the use of the hydraulicreactive power ampliiing system is disclosed by Fig. 1. Here thestandard hydraulic equipment illustrated comprises a fluid pressuregenerating system. This includes a reservoiror liquid holding tank 6, ailuid gear pump 7, its driving motor 8, electrical power source 9, fuseand switch unit 10, and pressure holding device 11, oil filter 12, andthe necessary hydraulic piping as shown.

A piston valve generally designated as 13 may be located in tank 6 toavoid dust. The tank will receive the used oil, and catch leakage oiland the reaction unit oil.

An operating cylinder generally designated as 37 carries heavy load W onits ram type piston. The hydraulic units described function incooperation as follows:

Pump 7 generates iluid power, which delivers a desired pressure byoperation of the pressure holding or relief device 11. Fluid pressure issuplied on one side of valve 13. Valve 13 consists of a valve body 14,which contains angularly moving piston 15. The valve body 14 and piston15 may be ported in many standard combinations, but

of cylinder 37 to lower load W.

Now valve pistons like piston 15, when under high fluid pressure, arenot moved easily with small power. Breakaway or starting friction, addsto the friction from the high pressures.

We however wish to move such a piston to position a typical heavy AloadW, with a small power electrical signal, such as, for example, thetorque motor M of Fig. l. The torque motor shaft 16, forms the inputshaft of one form of my hydraulic reaction power ampliier, generallydesignated as 17, to have its small power increased so as to be able toeasily change the heavy piston 15, in its load controlling functions asare described above.

Fig. l shows uid pressure from the pressure source 7, as being piped tothe jet arm, of the amplifying unit 17, through up pipe 18, swivel joint19, and exible hose 20.

Figs. 2, 3 and 4 show an enlargement of the form of my inventiongenerally designated as 17 on Fig. l. Here I show reaction base 21mounted on output shaft 22, axially in line with input shaft 16. Thisbase 21 contains guide blocks 21a, xed to base 21. In these bored guideblocks 21a, are parallel shafts 23 and 24. These two shafts are normallycentered in base 21 by lugs 25, fastened at the center of each shaft 23and 24. Two centering springs 26, per shaft, are arranged between blocks21a and the associated lug 25, on each shaft so as to center each shaftin its guide block 21a, when the jet impingement is at zero. A pair ofreaction blocks 27 are fastened to the opposite ends of shaft 23. Asimilar pair of blocks 27 are also fastened to the opposite ends of theshaft 24. These blocks have their adjacent faces shaped to efficientlyreceive jet -fluid impingement in their functioning usage.

Cradled between guide blocks 21a and fastened to the input shaft 16, isjet discharging arm 28. This arm has fluid under pressure supplied toits interior from pipe on Fig. l. The rather stiff uid hose 20 is movedaround joint 19 as the system changes its angular positions by means ofa stiff arm 29 fastened to one end of the output shaft base 21. Here themajor bending of the fluid hose is by output power, and the slightflexibility needed between the reaction base 21 and the jet arm 28, issupplied by the relatively long hose section 30 with minimum resistance.

If this design is used to automatically move its output shaft piston toa mid-point or block position when the opposing torque motor powers areequal, a special centering device may be used to bias the input shaft tosaid mid-point block position, similar to that shown on my Patent No.2,657,327, and the reason may be the same as there.

In Fig. 3, plan view, the jet arm is shown centered, as if at the momentthere is no rotative effort. .T et arm 28 discharges fluid under highpressure at its opposite ends and so balances jet reaction thrust whichwould cause pivoting friction. -A static jet arm holds its output shaftstill, and exactly in its angular line, with the high pressure jetsdischarging clearly between, but closely to, the adjacent impingementblocks 27.

A slight counterclockwise movement of the jet arm will start impingementagainst two of the blocks 27 diagonally disposed, causing shaft 24 toinstantly slide I; of an inch or so outwardly by impingement againstreaction block 27 thereon, at the same time, shaft 23 instantly slidesin the opposite direction by the same amount from the opposite endimpingement. This slight endwise shifting, is so that the dischargefluids will miss the adjacent reaction blocks not being used. ExtendedFigures 3a and 3b show the above shifted relations of the reactionblocks at each end of unit 17, when there is counterclockwise effort ofthe input shaft 16 driven by the small torque motor M, or by a returnspring if provided.

At the instant of completion of the shaft shifting as above, a heavilyamplified counterclockwise power assist begins. The amount of the powerassist depends on the angular displacement of the jet arm 28 and in turnits control of minimum to full impingement.

The output shaft will therefore be moved in a counterclockwise directionby a power assist of .a value limited only by the hydraulic design.

The above movement will continue because the output shaft and itsreaction arms will move to follow the jet arm lead all of the time, upto the rotative limits of the system.

Similarly, clockwise movement of the jet arm from a position centered inblock 21 will cause instant shifting of the slidable shafts 23 and 24,with clockwise reaction power assist in that direction for the durationof that jet arm displacement. Again, the amount of the clockwise powerassist will be governed by the degree of minimum to full bias lead ofthe jet arm, as is described.

The arrangement of the invention as described above allows the smallpower of the shiftable high pressure jet arm to lead its reactionpowered output shaft in any angular movements within the range of thedesign.

Shoulders 31 limit the displacement of jet arm 28 in case outputresponse is sluggish. If the input shaft 16 is subject to manualactuation, as in vehicle stealing, shoulders 31 also serve :as reservecoupling means in case of failure of the fluid reaction power.

While Fig. l illustrates a usage and hydraulic hose arrangement for lessthan 360 degrees of rotation, the full 360 degrees, or more, can be hadby using a standard revolving joint centered on the axis of shafts 16and 22.

While the vabove reaction blocks are slidably mounted to miss thedischarge of spent liuid, they can be individually pivoted to the base21, for the same reason, but may have lower power reaction eiciency.

Figs. 5, 6 and 7 illustrate enlarged details of another arrangement ofthe invention. Here again is shown an input shaft 50 in axial alignmentwith a power-moved output shaft 51, both rotating in the same directionand mechanically but loosely coupled by a nesting valve bar 52 fastenedto the input shaft 50, and nested in the reaction base 57, which isattached to the output shaft. This coupling gives safety in the case ofhydraulic pressure failure.

Valve bar 52 controls the division of flow of liquid between vanes orducts 53 and 56 for one movement and vanes or ducts 54 and 55 for theopposite movement.

In this arrangement, -uid under pressure enters at housing port 58,thence around annular space 59 and through holes 61, and so into thehollow end of the output shaft 60, and into the inside of the reactionbase 57.

Fluid 67 is thus delivered to the reaction base 57 in a manner to avoida flexing hose problem.

Input shaft 50 is fixed to the sweep valve 52, which is balanced by uidunder high pressure all around it. A fixed housing 62 is made to enclosethe above reaction parts, and is provided with outlet 63 to which a pipemay be connected so that the spent reaction fluid will return to thereservoir. This housing 62 may be lined with cellular rubber 64 toabsorb used fluid noise. The balanced sweep valve 52 has clearance onboth sides as at 65, and sweep clearance, without friction, over thedischarge ports. This valve -sweeps over its ports in its uid directingmovements. It does not have to be tight, and to avoid friction, shouldnot quite touch. Raised portions 66 do not serve as valve seats, but asstops.

Packing glands 68 are preferably provided, except that the outer one maybe omitted if there is a surrounding tank as in Fig. l, and the innerone can beomitted if extreme ease of actuating the input shaft 50 isrequired.

Fig. is an end view showing housing 62 enclosing the reaction units asabove. It illustrates valve 52 as static with no rotative effort. Inthis condition, the reaction base 57 stays in an angular position whichcenters exactly about the static valve 52. This is because, when thevalve 52 has no lead, it divides the tluid pressure into four equal andpower-cancelling forces. Hence, there is zero rotative elort for theoutput shaft 51.

If and when the input shaft 50 has slight angular rotative displacement,there is immediate valving for reaction power to move base 57, andv itsshaft 51, always in a direction tending to center it about valve 52.This power movement will continue until the reaction base is againcentered about the valve 52, or nearly enough so that the reaction forceremaining cannot move shaft 51.

The value of the power thus added to move the output shaft is limitedonly by the design.

In Fig. 5, the valve 52 is shown static, thus it divides the Ifluidreaction flow in equal and opposing directions, which yields zero outputshaft rotation.

Suppose the input shaft is static from zero rotational effort, and thereis suicient foreign effort to overcome and move the output shaftangularly. Then, andin that case, with the valve static, the reactionvanes will be opened whatever amount is needed to oppose such a foreignforce. If the foreign force is terminated before the valve moves, thereaction will restore the output shaft to its former position with thevalve in neutral or balanced position.

In other words, this invention makes a master out of the input shaft,and a slave out of the output shaft, with the latter controlled bygreatly amplified power.

It is vital to realize that any bias of the valve 52 angularly, willyield a powered action to move base 57 instantly in that same direction,in an effort to maintain centering about valve 52, for neutralizing itshydraulic reaction. v

Figs. 8, 9 and l0 show and illustrate an arrangement wherein input shaft75 is again in axial alignment with output shaft 76, both rotating inthe same instantaneous direction, and again being loosely coupled.

In this arrangement fluid pressure enters at 77, into annular chamber78, thence into the recessed part of shaft 76, thru holes 79, and intothe chamber of jet arm 80. The liquid in jet arm 80 is under fullpressure at all times that the equipment is being used because the jetorifices at each end are of so much smaller area than the crosssectionof the uid pressure piping at any point as to make the piping resistancenegligible.

Under static conditions of this unit, output shaft 75 will remaincentered, with its jets dividing equally between the two sides of thereaction blades 83 and 84, at both ends, thus neutralizing the reactionthrust.

If input shaft 75 is biased to lead in a clockwise rotation, a controlarm 81 moves with it. At each end of arm 81 is a blade 82, fastened tothe ends of arm 81, and acting as a tooth engaging a notch 85 in arm 86on reaction blade 83 or 84. Various means may be used to avoid play. Forexample, blade 8 may be a bendable member snugly engaged by bothassociated parts. Also, gear segments could be used.

Reaction blades 83 and 84 are pivotably mounted on pins, in opposite endextensions 87 of jet arm 80.

This combination of arm 81, and blades 82 fastened in its opposite ends,engaging reaction arms 86 functions, so that a clockwise bias of theshaft 75, rocks the reaction blades 83 and 84 in the opposite angulardirection, and so shifts the knife edge, that more jet fluid is receivedby the blades on one side thereof than the other. This provides areaction power assist, to output shaft 76, of slight to maximum forcedepending on the degree of the bias lead of shaft 75.

Similarly, when input shaft 75 is biased in a counterclockwisedirection, it moves its associated reaction blades so that uid willimpinge more on the other sides of blades 83 and 84, to move the outputshaft in a counterclockwise direction by reaction power assist.

The pivotal axis for reaction blades 83 and 84 should be located intheir various positions so that the forces of the jet stream on themwill be substantially balanced. If any departure from balance is to beencountered, it is preferable for most uses that it be in the directiontending to swing the reaction blades toward their neutral positions. Ifthis is not accomplished by the form shown, the pivot axis should bemoved closer to the knife edge until it is accomplished.

The arrangements shown in Figs. 5 to 10 require a fluid pressure sourcesuch as that represented by gear pump 7 in Fig. l.

The designs of Figs. 5 to 10 have high reaction efliciency, since theylend themselves to a vane shape which will yield degrees plus, change inthe direction of the lluid flow. All spent fluid discharges almostperpendicular to the plane through the point of discharge and coincidingwith the axis.

Now, in all of the arrangements disclosed herein, the amount of thepower assist in a particular design, is a function of the angular leadof the input shaft over the output shaft, in any movements. A thin leadmeans small power amplification because of minimum reaction. A stronglead means full power assist and fast output shaft movements therefrom.

In using any of the arrangements of this invention as a steering assist,we may install centering springs between the input and output shafts, as69 in Fig. 7 and 91 in Fig. 9. Such centering springs should center thevalve (or jet arm) when lead (moving) effort is discontinued. It iscontemplated that, for steering assist the unit might be installed in anexisting type of steering column, between the worm assembly and thesteering wheel. Present steering column shafts have road feel at thewheel now, from slight road wheel changing. The use of centering springssuch as 69, on Fig. 7 will retain the road feel, while using thesteering assist, which so many drivers like.

The amount of fluid assist can be limited by the fluid pressure.

In all of the illustrated forms, the gradations of reaction thrustprovide smooth action and substantially eliminate hunting. At the sametime, full available power is instantly available when needed, and iscalled forth by a minute movement of the input shaft.

All of the illustrated forms are suitable for use with high hydraulicpressures which with some apparatus might be subject to foaming troubleand resultant nonuniformity. Here any foam formed is immediately drainedfrom the unit and returned to the reservoir where it has time to releaseits air and return to the solid liquid state. In all of the units, thisquick removal of foam may be ensured by providing vanes or slopingsurfaces on the periphery of the housing directing all the jet liquidoutwardly or downwardly to beyond the path of the movable control parts.There may be a deeper drainage bowl than illustrated.

I claim:

l. A hydraulic-reaction control device, including means for supplyingliquid under pressure; reaction means receiving said liquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherdirection about the axis and balanced as to forces other than torqueabout the axis; and output means driven by said reaction means; saiddevice also including a control device 'readily pivotable about saidmain axis and associated with said reaction means to be relativelydisplaceable as to it in either direction angularly from a neutralrelative position, in which neutral position it causes the jets to beneutralized as to rotational force about the axis, displacement of saidcontrol means in either direction ass-2,917

from said neutral relative position causing said jets to bepredominantly discharged in a direction to exert "a Aforce on thereaction means in the same direction as the direction of saiddisplacement, and input meanstor controlling .said control means, saidinput means and output means being pivotable about said main'axis.

2. A hydraulic-reaction control device, including means for supplyingliquid under pressure; reaction means receiving said liquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherdirection about the axis and balanced as to forces other than torqueabout the axis; and output means driven by said reaction means, saiddevice also including a control device readily pivotable about said mainaxis and associated with said reaction means to be relativelydisplaceable as to it in either direction angularly from a neutralrelative position, in which neutral position it causes the jets to beneutralized as'to rotational force about the axis, displacement of saidcontrol means in either direction from said neutral relative positioncausing said jets to be predominantly discharged in a `direction toexert a force on the reaction means in the same direction as thedirection of said displacement.

3. A hydraulic-reaction control device, including means for supplyingliquid 'under pressure; reaction means receiving said liquid from saidmeans, pivotable about a .main axis, designed 'to discharge jets ineither direction about the axis and balanced as to forces other thantorque about the axis; and output means driven by said reaction means,said device also including a control device readily lpivotable aboutsaid main axis and associated with said reaction means to be relativelydisplaceable as to it in leither direction angularly from a neutralrelative position, in which neutral position it causes the jets to bencutralized as to rotational force about the axis, displacement of saidcontrol means in either direction from said neutral relative positioncausing said jets to be -predominantly discharged in a direction toexert a force on the reaction means in the same direction as thedirection of said displacement.

4. A hydraulic-reaction control device, including means for supplyingliquid under pressure; reaction means receiving said lliquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherdirection .about the axis and balanced as to forces other than torqueabout the axis; and output means driven by said reaction means, saiddevice also including a control device readily Vpivotable about saidmain axis and associated with said reaction means to be relativelydisplaceable as to it in `either direction angularly from a neutralrelative position, in which neutral position it causes the jets to beneultralized as to rotational force about the axis, displacement Yofsaid control means Vin either direction from said neutral relativeposition causing said jets to be predominantly discharged in a directionto exert a force on the reaction means inthe same direction as thedirection of said displacement; .the hydraulic forces on said controlmeans being substantially balanced so as to permit its control bydelicate forces.

5. A hydraulic-reaction control device, including means for supplyingliquid under pressure; reaction means receiving said liquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherdirection about the axis `and balanced as to forces other than torqueabout the axis; and output means driven by said reaction means, saiddevice also including a control device lreadily pivotable about saidmain axis and associated with said reaction means to be relativelydisplaceable ,as to it in either direction angularly from a neutralrelative position, in which neutral position it causes the jets to beneutralized as to rotational force about the axis, .displacement of saidcontrol means vin either direction from said neutral relative positioncausing said jets to be predominantly discharged in a direction to exerta force on the reaction means in the same direction .as the .direc- .18tion yof vsaid displacement; the hydraulic forces on said control meansbeing substantially `balanced and its zcontrol .being exerted free fromvalving contact Yso as to permit its control by .delicate forces.

, 6. A hydraulic-reaction control device, :including `means .forsupplying liquid under pressure; reaction means .receiving :said liquidlfrom said means, pivotable about ra main axis, .designed to dischargejets in either direction about the axis and balanced as to forces otherthan torque about fthe axis; and output .means driven by said reactionmeans, .said device also including a control device readily pivotableabout said main axis and .associated with said reaction .means to berelatively displaceable as to itin either direction angularly from aneutral relative position, in which neutral position it causes the .jetsto be neutralized as to rotational force `about the axis, displacementof said control means in either direction from said neutralrelative'position causing said jets to be predominantly discharged in adirection to exert a torceon the `reaction means in the same directionas the direction otsaid'displ'acement; the-hydraulic forces on saidcontrol means being substantially balanced and its control beingvexerted free from valving contact Vso as to permit its control bydelicate orcesgrand said .input means being biased toward said neutralrelative position, and said input lmeans being loosely coupledmechanically to the output -means to exert thrust thereon independentlylof the hydraulic thrust if the .output means fails to be moved by thehydraulic thrust Valone within the range `ot relative movement permittedby the loose coupling.

7, A hydraulic-reaction control device, including means for supplyingliquid Vunder pressure; reaction means receiving said liquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherdirection .about the axis and balanced yas to forces other than torqueabout the axis; and output means driven by said reaction means, said`device also including a control device readily -pivotable about saidmain axis and associated with said reaction means to be relativelydisplaceable as to it in either direction angularly from a neutralrelative position, in which neutral position it causes the .jets to .beneutralized as lto rotational force about the axis, displacement of,said control means .in either direction from said neutral relativeposition causing said jets to be predominantly discharged in a directionto exert a force on the reaction means in the Asame direction asthe-direction of said displacement; the hydraulic forces on said controlvmeans being substantially balanced and its oon- :trol being .exertedfree from valving contact so as to permit its control by delicateforces; and said input means being loosely coupled mechanically to theoutput means to exert thrust thereon independently of the hydraulicthrust if the .output means fails to be moved bythe Yhydraulic thrustalone Within the range of relative movement permitted by the loosecoupling.

8. Ahydraulic-reaction control device, including means for supplyingliquid under pressure; reaction means receiving said liquid from saidmeans, pivotable about a main axis, designed to discharge jets in eitherldirection about the axis land balanced as to forces other than torqueabout the axis; and output means driven by said reaction means, saiddevice also including a control device readily pivotable about said mainaxis and associated with said reaction means to be relativelydisplaceable as to it in either direction angularly from a neutralrelative position, in Whch neutral position it causes the jets to beneutralized as to rotational force about the axis, displacement of saidcontrol means in either direction from said neutral relative positioncausing said jets to be predominantly discharged in a direction to exerta force on the reaction means in the same direction as the direction ofsaid displacement; the hydraulic forces on -said control means beingsubstantially balanced and its control being exerted free trom 'valving:contact so as .to permit ,its

9 control by delicate forces; and said input means being biased towardsaid neutral relative position.

9. A hydraulic-reaction amplifying device including a liquid conduit;reaction means, .pivotable about a main axis, receiving liquid from saidconduit and designed to discharge jets balanced about the axis as toradial thrust and directed to provide reaction torque about the axisselectively in either direction; output means driven by said reactionmeans; and input means; said device including control means readilymovable lby the input means for selectively etlectuating the reactionmeans for discharging the jets in one direction about said axis, or inthe opposite direction about the axis, or with a neutral eiect as tomovement about said axis.

10. A hydraulic-reaction control device of high output power, includinga master shaft and a slave shaft both mounted to be pivotable more thana full revolution about a main axis, a control element carried by themaster shaft to be moved by it and reaction means carried by and movingthe slave shaft, means for delivering to the reaction means liquid underpressure and subject to control by the control element; the controlelement having a neutral relative position with respect to the reactionmeans, in which any rotational force exerted by the liquid on thereaction means is neutral, and being relatively shiftable from theneutral position in opposition directions by minute force and, as itshifts, causing the liquid to exert progressively increased effectiverotational thrust on the reaction means in the direction of the shift,whereby the power available from the liquid in its coaction with thereaction means makes the slave shaft substantially follow the movementsof the master shaft.

References Cited in the le of this patent UNITED STATES PATENTS 919,289Lake Apr. 20, 1909 999,776 Gill Aug. 8, 1911 1,519,444 Fales Dec. 16,1924 2,426,606 ,Goti Sept. 2, 1947 2,598,177 Kalle May 27, 1952 FOREIGNPATENTS 169,621 Germany Nov. 5, 1904 667,816 Germany Nov. 11, 1938677,803 Germany July 3, 1939 698,473 Germany Nov. 11, 1940

